Conversion of foliar residues of Sansevieria trifasciata into adsorbents: dye adsorption in continuous and discontinuous systems

The study analyzed the potential of leaf powder prepared from the residual leaves of the species Sansevieria trifasciata, as a potential adsorbent for methylene blue (MB) removal. The equilibrium was reached fast for almost all concentrations after 60 min, obtaining the maximum capacity of 139.98 mg g⁻¹ for 200 mg L⁻¹. The increase in temperature disfavored the dye adsorption, with the maximum adsorption capacity of 225.8 mg g⁻¹, observed for 298 K. The thermodynamic parameters confirmed that the adsorption process is spontaneous and exothermic. A direct sloping curve was established for the fixed bed, with breakthrough time (t_b), column stoichiometric capacities (q_eq), and the mass transfer zone lengths (Z_m) were 1430, 1130, and 525 min; 60.48, 187.01, and 322.65 mg g⁻¹; and 8.81, 11.28, and 10.71 cm, for 100, 200, and 500 mg L⁻¹, respectively. Furthermore, in a mixture of several dyes, the adsorbent obtained the removal of 51% of the color.